The positivity check is unnecessary -- it's a size_t.
The positivity check is unnecessary -- it's a size_t.

Also fix type warnings.

palashahuja/mlpack,theranger/mlpack,ajjl/mlpack,stereomatchingkiss/mlpack,ranjan1990/mlpack,darcyliu/mlpack,ranjan1990/mlpack,darcyliu/mlpack,ajjl/mlpack,theranger/mlpack,ranjan1990/mlpack,darcyliu/mlpack,palashahuja/mlpack,stereomatchingkiss/mlpack,palashahuja/mlpack,stereomatchingkiss/mlpack,ajjl/mlpack,theranger/mlpack